As background, ships are typically made in transverse sections that are joined together in dry dock. These sections have horizontal steel ribs (stiffeners) that are attached to the walls (bulkhead) of the ship section. These stiffeners, are also known as erection beams or bulb-flat stiffeners and are used to provide support to and prevent buckling of the panels used in shipbuilding. The bulb-flat stiffeners are welded at their edge to ship sections (portions of the hull) prior to the attachment of the transverse sections to each other. They are also used with interior bulkheads (vertical walls) as well as with deck plating (flooring). For the hull and bulkheads, stiffeners are attached to the hull and bulkheads in a vertical orientation. When used with decking, they are used in a horizontal orientation. Bulb-flat stiffeners are in many respects analogous to the wall studs and floor joists typically used in home construction.
When a ship section is made, the bulb-flat stiffeners extend past the ends of the wall section and must be trimmed in the ship building process, i.e., in the assembly of the ship sections. In the ship building process, a new section is brought into place next to the end of the previously assembled sections and the amount of extending bulb-flat stiffener that needs to be trimmed off is marked for cutting. The new section is moved away from the assembled sections and a cutting torch (oxygen and gas or oxygen and acetylene) is then used to cut off the excess portion of the stiffener. After the ends of the bulb-flat stiffeners are trimmed to the appropriate length, the edge of the new section is butted against the edge of the previously assembled sections of the ship that has already been welded in place and the two abutting sections, i.e., the abutting edges (ends) of the hull and the bulb-flat stiffeners are welded together.
In present day practice, the bulb-flat stiffeners are trimmed entirely by hand, i.e., a section assembler takes a cutting torch and trims off the excess portion of stiffener by means of a free-hand, visual inspection (xe2x80x9ceye-ballxe2x80x9d) method. Unfortunately the work place environment is typically not worker friendly in that the worker doing the bulb-flat cutting often works more than a hundred feet in the air on temporary scaffolding in a dark and dirty environment that is not at all conducive to making straight and accurate cuts. As a result, the free-hand trimming of excess bulb flat ends can result in large gaps between adjacent bulb-flat stiffener ends when the sections are brought into position for final assembly. It is not unusual for it to take an hour or longer to fill in the gaps between the ends of the bulb-flat stiffeners when the ends are welded together.
Although some efforts have been made to mechanize cutting of various members in other industries, none of those devices meet the needs of the ship building industry. For example, U.S. Pat. No. 5,160,549 (Murphy) discloses a cam follower device for cutting angled finned tubes. This device relies on completely supporting the work piece in the cutting machine. U.S. Pat. No. 3,190,628 (Litzka) describes a device for cutting center sections from I beams but, here again, the device relies on supporting and/or clamping the device and the work piece to a solid work bed. U.S. Pat. No. 4,180,248 (Benko) is directed to a sill cutting unit but here the machine is supported independently of the work piece. In all three patents, the units are very large and do not provide the portability needed for use in the ship building arts. U.S. Pat. No. 4,471,948 (Holmes) is directed to a cutting unit that is attached to the work piece but in this instance the torch travels in an arc about a pivot pin with a cam used to maintain the cutting torch at a relatively constant distance from the work piece.
None of these devices teach or suggest a portable unit for making straight line bevel cuts with provisions for cutting a large bulb member at one edge of the work piece that must be fashioned into a scoop to allow for high-quality and high-strength welds required in the ship building arts. Further none of these references teach how such a device might be adapted for the varying cutting angles required in joining the angled sections of a ship or aligning the torch for cutting at but not into the attached hull of the ship. None of these references teach a device by which the welding torch can be aligned repetitively at various angles with a high degree of accuracy. None of these reference teach how a cutting torch can be set to ignite and weld at a predetermined optimal gas and oxygen level without constant adjustment of the cutting torch each time the unit is used.
As such, it is an object of the prevent invention to provide a cutting torch unit capable of cutting a flat-bulb stiffener using a single drive unit.
It is another object of the present invention to provide a cutting torch unit capable of repetitively cutting a beveled edge on a flat-bulb stiffener.
It is another object of the present invention to provide a cutting torch unit capable of cutting a flat-bulb stiffener at the point it meets an attached plate without damage to the attached plate.
It is another object of the present invention to provide a cutting torch unit capable of cutting a flat-bulb stiffener at an angle necessary for joining angled sections of a ship.
It is another object of the present invention to provide a cutting torch unit capable of being quickly and accurately secured to the work piece for precise cutting.
It is yet another object of the present invention to provide a cutting torch unit with a torch that is maintained at an optimal level of cutting efficiency without repetitive adjustment of fuel and oxygen flows each time a cut is made.
It is another object of the present invention to provide a cutting torch unit that is capable of forming a scoop in the bulb end of a flat-bulb stiffener for optimal welding conditions.
It is another object of the present invention to provide a cutting torch unit that is quickly broken down into portable sections for meeting adverse shipyard work conditions.
It is another object of the present invention to provide a torch holder with an alignment mechanism and angle indica that allow for quick and accurate alignment of the cutting torch.
It is a further object of the present invention to provide a cutting tool that is easy and convenient to carry, handle, and manipulate under shipyard conditions, that is, in cutting bulb-flat stiffeners using scaffolding extending upward 150 feet or more in what is typically a dark and debris laden environment.
Another object of the present invention provides consistent, high quality weld joint parations in a very short time.
It is yet another object of the present invention to provide a beveled edge and scoop area at allow for rapid and convenient access to the joint region during the welding process.
Another object of the present invention is to provide a cutting torch assembly for cutting a variety of structural materials including T- and I-beams.
It is another object of the present invention to provide a means for quickly positioning and moving the track of a track and carriage system with respect to its supporting assembly.
The foregoing and other objects, features and advantages of the invention will become apparent from the following disclosure in which one or more preferred embodiments of the invention are described in detail and illustrated in the accompanying drawings. It is contemplated that variations in procedures, structural features and arrangement of parts may appear to a person skilled in the art without departing from the scope of or sacrificing any of the advantages of the invention.
To meet these objectives, the present invention features a cutting tool for workpiece cutting that comprises 1) a clamp that is sized to attach to the workpiece, 2) a rotating platform that is rotatably attached to the clamp, 3) a latch with a first latch member attached to the rotating platform and a second latch member latching to the first latch member. Prior to latching, the second latch member as assembled so have to have 1) a track attached to it with a carriage moveably attached to the track , 2) a positioning arm attached to the carriage, and 3) a cutting torch holder attached to the positioning arm. The latching mechanism minimizes weight and bulk during the initial workpiece clamping after which the rest of the cutting assembly cam be quickly latch to the clamped assembly with a minimum of further alignment and setup time.
The invention features a quick acting xe2x80x9cVise-Gripxe2x80x9d type clamp to quickly and accurately clamp the cutting tool to the workpiece. The clamp uses a four pivot pin mechanism with a stationary jaw attached to a moveable jaw with a first pivot pin, a connecting handle attached to the stationary jaw with second pivot pin, a moveable handle attached to the connecting handle by a third pivot pin and to the moveable jaw with a fourth pivot pin. This four pin arrangement allows for quick and accurate alignment of the clamp with the workpiece and affords a quick and sure locking clamp.
To adjust the clamp for different workpiece thickness, the clamp features a moveable locking rod that is attached to the moveable jaw of the clamp. The moveable locking rod is locked to the moveable jaw with two nuts. The rotating platform has a hole formed in it for receiving a fixed circular center post projecting upward from the clamp and serving as the center of rotation for the rotating platform. An arcuate slot is formed in the rotating platform for receiving a threaded shaft with an attached handle. The treaded shaft passes through the arcuate slot and into a threaded hole in the clamp and locks the rotating platform to the clamp when it is rotated into the threaded hole using the attached handle. The rotating platform also has a hole in it for receiving a thumb screw that is screwed into a threaded hole in the clamp in order to accurately and quickly set the rotating platform to an exact ninety degree crosscut position.
The track and carriage of the current invention has a track with a housing that has a lead screwed rotatably mounted in it. The lead screw is rotatably driven by a motor attached to it by means of a coupling clutch. The lead screw linearly drives a block with an attached slide. The track also has a U-shape cover attached to the housing to keep dirt and debris from entering into the housing. To achieve protection of the housing and its associated parts, its was necessary to devise a way in which to cover the housing while at the same time driving the moveable carriage with components that has been covered. To this end, a U-shaped carriage was designed and attached to the track slide. The carriage was designed in a U-shape having a U-shaped slot formed in it so that the U-shaped cover would fit into the U-shaped slot. In effect, the housing cover passes through the specially designed U-shaped carriage.
One of the features of the present invention is its application to align and set up the tool using its light weight base. It is too be appreciated that working with a small unit is a lot more convenient than working with a heavy and bulky machine especially on rickety scaffolding under dark and inhospitable conditions. The slam latch makes its possible. It essentially divides the tool into two parts with initial alignment of the entire machine done on the basis of its much smaller clamping portion. Once the base is clamped down, the remainder of the machine can be easily locked into place using the slam latch.
The first part of the latch, i.e., the part associated with the clamp comprises latch member with 1) a hock with an outward facing groove, aid 2) a latch with an outward facing notch. The second latch member comprises 1) a first aperture that receives the hook, and 2) a second aperture that receives the latch, i.e., the hook and latch project into holes in the second member when the second member is latched into place. The first aperture has a pin (rod) passing through it with its ends secured in the latch member. In operation this pin is placed in the groove formed in the hook. The pin and groove combination serves as an axis of rotation as the other end of the second member is rotated down on the latch. The second aperture has a retractable plunger pin projecting into it and secured to the second latch member. The engagement of the plunger pin with the notch in the latch effectively locks (latches) the two latch members together.
Although the slam latch can be securely attached to the track with bolts or other fasteners, this severely limits the operational range of the cutting tool. As such, it was important to devise a simple way to reposition the upper latch member to the track. To this end, a slot was formed in the base of the track. Although only one slot need be used, the second, spaced-apart slot adds strength and rigidity to the entire assembly. A groove was also formed in the upper latch member that aligned itself with the slot formed in the base of the track. A circular passage was formed in the upper latch member at right angles to the groove. A lock plate was constructed with a flange formed at its upper edge at right angles to the body of the lock plate as well as having an aperture formed in it. The lower portion of the lock plate which is opposite the flange, extends through the slot formed in the base of the track until the flange contacts the upper surface of the base of the track. The base of the plate also extends into the groove in the latch member. The plate is moveable lengthwise along the slot. A cam lock is formed as a cylinder with a cam lobe projecting outward from the cylindrical shape of the cam lock. The cam lock is rotatably secured in the passage formed in second latch member. The cam lock is rotatably secured in the passage formed in the upper latch member and passes through the aperture formed in the lock plate. The flange of the lock plate draws the base of the track downward to contact an upper surface of the upper latch member as the cam lobe rotates downward in the aperture formed in the lock plate and urges the lock plate downward to lock the base of the track to the upper surface of the latch member.
The next component of the invention is the positioning arm. Generally the purpose of the positioning arm is to position the torch away from the clamp and track and carriage during the cutting operation so as to avoid damage to these components from the heat and molten metal produced during the cutting process. The positioning arm is made up of a housing that is attached to the carriage. An arm moves into and out of the housing and has a slot formed in its side. A rack is mounted within the arm. The teeth of a pinion gear project through the slot of in the arm and engage the rack teeth. A shaft has the pinion gear attached at one end and a handwheel attached at the other.
When cutting bulb flats at an angle, a straight line cut will leave the lower end of the bulb flat projecting beyond a plane passing through the edge of the cut at the bulb surface. This tends to leave a large between the bulb flat at every position except where the lower edge of the bulbs project outward from the cut and touch each other. As such, it is desirable to move the torch laterally as well as along the direct of cut when cutting the bulb portion. In the past, the only way to achieve both a forward and a lateral cut was with a double drive device, i.e., a track moving the carriage in a first direction while a second carriage moves the torch laterally, typically by moving the first carriage. Thus it is one of the object of the present invention to achieve both forward and lateral movement of the cutting torch using only a single moving carriage.
This was accomplished by using developing a lateral torch position manipulator. Such a manipulator comprises a fixed block (non-moveable) unit attached to the carriage and a cam pattern block attached to the track. A movable block unit has the position arm attached to it and is moveably attached to the fixed block unit. The movable block unit has a cam follower arm with a cam wheel that contacts the cam pattern block. As a result, the movable block unit moves laterally with respect to the fixed block unit in response to the cam wheel following the cam pattern block.
The fixed block unit has a housing; attached to the carriage with stationary end blocks attached to the fixed housing and a stationary spring block also attached to the housing. A rod is attached at one end to the stationary end block and at the other end to the spring block. The fixed block unit also contains a moveable block. The moveable block has a hole formed in it with the rod passing through the hole. Since this is the only restraint on the moveable block and the radius of the hole is larger than the radius of the rod, the moveable block is able to move along the rod between the end block and the spring block. A tension spring is connected at one end to the moveable block and at the other end to the spring block. As a result, the spring pulls the moveable block toward the spring block. Since the moveable block is connected to the moveable block unit by means of a plunger projecting into the moveable block. As a result, any force that tends to move the moveable block outward toward the end block will result in a counter force from the tension spring tending to bull the moveable block unit back toward the track. In effect this is the method by which the cam follower wheel is held against the track and cam block.
As shown in figure twenty, one of the limitations of the present invention is that it is not possible to make angle cuts when the work piece to be cut is attached to a wall. As is evident, rotation of the unit angles the cutting torch way from the wall and bring the positioning arm and corner of the track in contact with the wall on the side opposite to the cut. To this end, it has been found that the installation of a second rotating platform that rotatably attaches the positioning arm to the carriage will eliminate this problem. As seen in figure twenty, rotation of the positioning arm toward the wall on the cutting side will bring the torch to a position where it will be able to completely cut the workpiece without doing damage to the wall.
The second rotating platform comprises to plates, a base plate that is attached to the carriage and a rotating plate attached to the positioning arm with the rotating plate also being rotatably mounted to the base plate by means of a pivot pin. Similar to the first rotating platform, the second platform as an arcuate slot for receiving a handled bolt that is received in a threaded hole in the base plate. The rotating the bolt into the threaded hole, the rotating plate is locked to the base plate. The arcuate slot allows such locking to take place throughout the range of angles through which the positioning arm is turned within the range permitted by the arcuate slot. A spring loaded plunger mounted on the rotating plate engages a hole in the base plate. By placing this hole at zero angle of rotation, it is always easy to return the positioning arm to its non-angled position. Rotational indicia on the rotating platform and a base line on the base which serves as a reference indicator, permits exact angles to be maintained through the job.
Another feature of the present invention torch holder that allows the torch to be manipulated in three directions: angularly into and out of a plane along the cut line, angularly in the plane along the cut line, and linearly in the direction to which the torch is turned. Indicia with respect to both angular manipulations allow torch position to be exactly controlled.
The torch holder is composed of a base plate which is typically attached to the positioning arm and which has a circular recess cut into it. A rotating plate is mounted for rotation in the circular recess and affords rotational positioning of the torch in the plane of the cut.
T two spaced-apart torch clamp brackets are attached at one of each of their ends to the rotating plate with the other end attached to the torch and transfers the rotational motion of the rotating plate to the torch. The torch clamp is also able to pivot in and out of the cutting plane as a result of the fact that the torch clamp is mounted for pivoting on pivot pins mounted in the two spaced-apart torch clamp brackets at the ends opposite the ends of attachment to the rotating plate. A spur gear mounted in the torch clamp engages a rack mounted on the cutting torch to move it in and out of the torch clamp.
Rotation of the rotating plate mounted in the base plate is accomplished by means of a screw that passes through a cylinder moveably mounted in a slot in the rotating plate. As the screw is turned, the cylinder is urged against the wall of the slot causing the rotating plate to turn in that direction. Rotational indicia on the rotating plate align with a pointer in a viewing window in the base plate to give an exact indication of the amount of rotation to which the torch has been subjected and allows for the reproducibility of the cutting process.
As noted the torch rotates into and out of the cutting place as a result of the mounting of the torch holder on pivot pins at the ends of the torch clamp brackets. Pivoting about these pins is accomplished by means of a spur gear mounted in the torch clamp brackets which engages a curved rack mounted in the torch clamp. The torch clamp bracket has angle indicia along the path of the curved rack. A pointer formed in a window of the torch clamp bracket enables exact determination and reproducibility of the requisite angle.
In cutting processes involving structural members such as I- and T-beams, it is oven necessary to move the torch in a variety of directions and at considerable distance from the motor driven carriage. To accomplish such cuts, a second positioning arm may be attached to the first positioning arm, typically at right angles to the first positioning arm. Generally the housing of the second positioning arm is attached to the arm moving in and out of the housing. As with the first positioning arm, the second positioning arm has a housing, an arm moving in and out of the housing, a slot formed in the arm, and a rack inserted into the interior of the arm and accessible by pinion teeth of a pinion mounted in the housing on a shaft driven by a handwheel at its opposite end.
In addition to the extended reach afforded by a second positioning arm, it often is desirable to make cuts in both flanges of an I-beam or to make horizontal cuts in the web of an I- and T-beam, To this end a different type of clamp has been developed as well as a base plate that allows the motor driven carriage to be moved from a vertical to a horizontal position.
To this end, a clamp has been developed for rigidly clamping to both edges of the flange on a T- or I-beam and then having a pivoting plate mounted on the clamp to permit orientation of the motorized carriage in either a vertical or horizontal position. The clamp comprises a base plate formed from a horizontal plate and a vertical plate, a stationary clamping block fixed to the base plate, a moveable clamping block moveably attached to the base plate and urged to and from the first clamping block by means of a threaded rod rotating in a threaded hole formed in a block attached to the base plate.
For vertical and horizontal orientation of the motorized carriage, a pivot hole is formed in the base plate and a pivot plate is attached to the base plate by means of a pivot pin passing through the pivot hole and attached at each end to the pivot plate. The pivot plate moves between vertical and horizontal positions as a result of rotation about the pivot pin.
The pivot plate can be locked in the horizontal position and in the vertical position by means of a first handled pin that engages a hole in the horizontal plate of the base plate to lock the rotating plate to the horizontal plate and by means of a second handled pin engaging a hole in the vertical plate of the base plate to lock the rotating plate to said vertical plate in a vertical position.
Finally it is noted that torch cutting is a difficult art with even the light and adjustment of the proper flow of fuel and oxygen a most difficult task and only correctly done after years of experience. Unfortunately the adjustment process must be done with virtually every cut and even the skilled tradesman, it takes its toll on cutting torch parts and valves. To this end, it has been found that a unique combination of quick acting on-off valves, pressure regulators, and flow control valves virtually eliminate the need for torch adjusting and consistently give high quality torch cuts. To accomplish such consistency a pressure gauge, a flow control valve, and a quick-acting on-off value are used to supply fuel to the torch. The torch valve itself may always be left completely open. Similarly the oxygen supply is first regulated with a pressure gage and then split into two flows, one for heating and one for cutting. The heating flow is next sent through a flow control valve and then to a quick-acting on-off valve. The cutting flow need only be sent through a quick-acting on-off value. Once the pressure and flow control valves have been set, not further adjustment of the fuel and oxygen supply lines need be made. The workman then need use only the three on-off valves (fuel, heating oxygen, and cutting oxygen) for all cutting
The foregoing and other objects, features and advantages of the invention will become apparent from the following disclosure in which one or more preferred embodiments of the invention are described in detail and illustrated in the accompanying drawings. It is contemplated that variations in procedures, structural features and arrangement of parts may appear to a person skilled in the art without departing from the scope of or sacrificing any of the advantages of the invention.